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SIT Group

537 ABC

537 ABC- ELECTRONIC FLAME

CONTROL DEVICE FOR INTEGRAL

MOUNTING ON SIT SIGMA

MULTIFUNCTIONAL CONTROLS

w w w . s i t g r o u p . i t

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537 ABC

The 537 ABC is an electronic flame safety device for controlling a gas appliance using

the principles of flame rectification.The 537 ABC automatic device has been designed for domestic gas appliances with or

without a fan in the combustion circuit; with direct ignition or ignition by means of an

intermittent pilot in applications which require either non-volatile or volatile lockout.

The 537 ABC family of products has been specifically designed for fixing on SIT 840,

845 and 848 SIGMA multifunctional controls by means of an exclusive plastic container

which integrates itself with the valve body and simplifies connection of the solenoid

valves.

BASIC FEATURES

- Compact design- Direct assembly on the gas control

- Incorporated igniter

- Direct burner ignition (DBI) or by intermittent pilot (IP)

- Manual reset function and remote signalling of the non-volatile lockout state

- Multiple plug-in connectors

- Utilises well established electronic technology for high reliability of operation

- Precise and repeatable timing

- Flame detection by ionization

- EC approval according to EN 298 standard

- Repetition of the cycle after loss off flame during operation

- Permanent lock-out visualization, a without thermostat input being present

- Suitable for applications at low ambient temperatures

Options available

- Fan and air pressure switch control

- Volatile lockout version for specific applications

- Possibility to connect an automatic safety thermostat in series with the

solenoid valve with manual lockout following its operation

- Different flame current sensitivity options may be specified

- Protection rating IP44

- Several pre-purge and safety timings can be tailored to the application.

NORMATIVE REFERENCE

EN 298

Automatic gas burner control systems for gas burners and gas-burning appliances

with or without fans.

DESCRIPTION

APPLICATIONS

The 537 ABC is an automatic ignition control for applications with intermittent

operation in accordance with EN298 for:- boilers with natural draught

- boilers with forced draught including dynamic control of the air pressure switch.

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537 ABC

Normal operation (natural draught or fan assisted)

During the waiting or purge time, Tw or Tp, the unit verifies that there is

no parasitic flame signal present, and that the internal circuitry is

operating correctly. If the unit is used on a fan-assisted application, the

air pressure switch is verified to be in the N.C. (normally closed) or

no flow position.

Upon powering the fan, the unit will not begin the operating sequence

until the N.O. (normally open) or flow position is activated on the air

pressure switch. After the scheduled waiting time Tw, or purge time Tp,

the built-in igniter and the gas valve are energized. This commences the

safety time, Ts. The ignition spark will ignite the gas and the flame will

be sensed by the HV electrode.

Upon sensing the flame, the HV spark will be suppressed and the gas

valve will remain energized. When the thermostat is satisfied, the valve

and fan are de-energized and the control returns to the stand-by mode.

The safety time of the 537 ABC has a constant duration in all operating

conditions and, in particular, does not depend on the moment the

pressure switch is switched over.

Resetting the unit

To reset the unit the reset switch is depressed. If a first reset is not

successful, wait at least 10 seconds before the next attempt.

OPERATION

TW TW

MV

VN

TS

BOILERS WITH

NATURAL DRAUGHT

DBI version

FAN ASSISTED BOILERS

DBI version

TP TP TS

P

EV

VN

TW TW

EV1

VN

TS

EV2

BOILERS WITH

NATURAL DRAUGHT

IP version

WIRING DIAGRAM

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TECHNICAL DATA

537 ABC

DIMENSIONS- 537 ABC with 845 SIGMA VERSION G3/4 ISO 228

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AMBIENT WORKING TEMPERATURE

-20 TO + 60 CHUMIDITY

95 % max at 40 C

SUPPLY VOLTAGE

230 Vac - 15 %, + 10 %, 50-60 Hz

POWER CONSUMPTION

10 VA

ELECTRICAL RATINGS

Gas valves: 230 Vac, 0.5 A, cos0.4

Fan: 230 Vac, 1 A, cos0.4 (optional)

Allarm: 230 Vac, 1 A, cos=1

ELECTRICAL CONNECTIONS

High voltage probe: male fast-on connector 2.8 mm X 0.5 mm

Flame detection probe: male fast-on connector 4.8 mm X 0.8 mm

Other connections: male Molex series 2599 suitable for female Molex series

3001 and 3002 or compatible.

PROTECTION DEGREE

Standard IP 40

IP 44 with gaskets

TIMING

Minimum waiting time Tw or purge time Tp: 1.5 ... 40 sec.

Maximum safety time Ts: 3 ... 60 sec.

FLAME SENSING

Minimum flame current: 0.5A

Recommended flame current: > 3 times the minimum current

FUSING

Internal: 4 A fast.

External: 3.15 A fast or less depending on the electrical loads.This fuse protects

the device in the event of overloading or short circuits and prevents the

intervention of the internal fuse.IGNITION

Ignition voltage: 15 KV at 30 pF load

Repetition rate: 25 Hz standard (1 : 25 Hz)

Max. length of the cable: 2 m

Spark gap recommended: 2-4 mm

MOUNTING

Integrated on SIT SIGMA multifunctional gas controls.